1. Field of the Invention
This invention relates generally to a data storage system, apparatus and processes of making and using the same, and in particular embodiments to a system, apparatus, and processes for reducing contamination at the head-disc interface of a disc drive apparatus.
2. Description of Related Art
Modern computers employ various forms of storage systems for storing programs and data. For example, various forms of disc drive systems have been designed to operate under the control of a computer to record information and/or retrieve recorded information on one or more recording discs. Such disc drives include hard disc drives which employ recording discs that have magnetizable (hard) recording material, optical disc drives which employ recording discs that have optically readable recording material, magneto-optical (MO) disc drives which employ recording discs that have optically readable magnetizable recording material, or the like.
Conventional disc drive systems typically include one or more recording discs supported for relatively high speed rotation on a rotary spindle hub. In systems employing more than one recording disc, the discs are typically arranged in a stack on the hub. The recording surfaces of such stacked discs are accessed by the read/write heads mounted on a complementary stack of actuator arms, which form a part of an actuator assembly. Typically, the actuator assembly has an actuator body that pivots about a pivot mechanism disposed in a medial portion thereof. A motor selectively positions a proximal end of the actuator body. This positioning of the proximal end in cooperation with the pivot mechanism causes a distal end of the actuator body, which supports the read/write heads, to move generally radially across the recording surfaces of the discs, such that the head may be selectively positioned adjacent any recording location on the recording surface, as the disc is rotated.
In a reading or recording operation, the heads are supported in close proximity to respective disc recording surfaces, while the discs are rotated with the spindle hub at several thousand rotations per minute (RPMs). The heads are moved in an array, in the generally radial direction of the disc surfaces, to align or register the heads with desired track locations on the disc surfaces. Once aligned or registered, the heads are operated to read or write information at desired track locations, while the disc (and, thus, the recording surface) spins at a relatively high rate.
The high rate of rotation of the discs produces a thin layer of air along each disc surface, moving at a high velocity in the direction of rotation of the disc surface. The layers of air, or air bearings, formed on the moving disc surfaces help support the heads in close proximities to, but slightly spaced from, the disc surfaces. However, when the disc rotation rate decreases, such as during power down, the air bearing effect decreases and the heads may be allowed to come into contact and rest against the disc surface. Typically, the heads are moved to a position adjacent designated portions of the discs suitable for contacting the heads, for example regions near the disc centers, before the air bearing effect decreases to a degree that allows head/disc contact. Once the disc rotation stops, the heads remain in contact with the respective disc surfaces until the next successful power up operation.
In such disc drive apparatuses, head stiction, or static friction between the head and disc surface, can inhibit the head and disc from breaking free of each other during power up and, thus, can result in a failure of the disc drive. Contaminants on the head and disc surfaces can increase the stiction effect and, thus, increase the likelihood of disc drive failure. For example, contaminants within the drive housing (such as those that outgas from the motor) tend to gather at the head-disc interface and cause the head and disc to stick together. In closed confines of a disc drive housing, contaminants tend to accumulate over time and can eventually exceed a failure threshold amount.
The degree of outgassing of oil from components of the disc drive motor depends, in part, on the type of motor used in the disc drive apparatus. For example, hydrodynamic motors of the type described in co-pending patent application Ser. No. 09/247,793, titled xe2x80x9cHydrodynamic Motor In A Head Disc Assembly,xe2x80x9d filed Mar. 1, 1999, which is assigned to the assignee of the present application, have a potential to expose a greater amount of oil to the environment than, for example, motors which employ sealed bearings. However, because of other advantages that are available with hydrodynamic motors, such motors are a preferred choice in various applications of use.
Thus, there is a need in the industry for a system, apparatus and process for minimizing drive failure by reducing the amount of contamination at the head-disc interface. There is a further need for such a system, apparatus and process which employs a hydrodynamic motor. In addition, there is a need for such systems, apparatuses and processes which are capable of being manufactured and implemented in a relatively simple and cost effective manner.
As discussed in more detail below, embodiments of the present invention address the above-noted needs by employing a porous sack containing a contaminant absorbent material. While porous sacks containing silica gel has been used in disc drive devices to absorb moisture, for humidity control, such silica gel sacks have been ineffective in absorbing contaminants, such as oils, other hydrocarbons and other contaminants which tend to accumulate within disc drive housings.
Accordingly, one advantage of preferred embodiments of the present invention is to address the above-noted need by reducing contamination in the internal environment of the disc drive apparatus, to minimize the accumulation of contamination at the head-disc interface.
Another advantage of further preferred embodiments of the present invention is to address the above-noted need by providing an efficient, cost-effective article and process that is relatively easy to manufacture and implement, for reducing contamination in the internal environment of the disc drive housing.
A preferred embodiment of the present invention involves a data storage system and apparatus which includes a housing defining an internal environment in which other disc drive components are contained. During operation, contaminants within the housing tend become vaporized and transported around various components in the housing interior volume. Such contaminants have a vapor pressure and a chemical composition dependent on the contaminant. The amount of vaporized contaminant in the environment varies with different environmental factors, such as temperature.
Various disc drive components contained within the disc drive housing include, for example, data storage discs, heads, the rotor of a disc motor, the head array actuator and other components well known in the art. In preferred embodiments, the disc motor is a hydrodynamic motor of the type described in co-pending patent application Ser. No. 09/247,793 titled xe2x80x9cHydrodynamic Motor In A Head Disc Assembly,xe2x80x9d filed Feb. 8, 1999. As described above, various components, such as hydrodynamic disc motor components, can have a tendency of outgassing contaminants into the environment within the interior volume of the housing.
Accordingly, in preferred embodiments, a suitable material is selected as an absorbent or getter for the contaminant, and is disposed within the internal environment of the housing interior. A preferred contaminant absorbent or getter materials include activated carbon or activated carbon composition. However, other embodiments may employ other suitable contaminant absorbent or getter material, including, but not limited to Tenax (a trademark of Buchem B. V. Corporation). According to preferred embodiments, the material (such as activated carbon) is contained within a bag or packet made of a suitably porous material, including, but not limited to polytetrafluoroethylene (PTFE), or the like. The packet may be readily placed within the disk drive housing interior, during manufacture, with minimal manufacturing complexity. In further preferred embodiments, the packet is placed in a location within the housing interior having a relatively high exposure to air-flow within the interior. In yet further preferred embodiments, the housing interior is specifically configured to provide an internal location which is exposed to a sufficient degree of air-flow and which receives and holds the packet of material. The volume of absorbent or getter material is preferably selected based on (to be capable of absorbing) the volume of contaminant expected to be outgassed or otherwise present within the disc drive housing during normal operational life.
Various advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention and its advantages, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there is illustrated and described specific examples in accordance with preferred embodiments of the invention.